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14 tháng 2 2017

a/ \(\left(a^2+4b^2-5\right)^2-16\left(ab+1\right)^2\)

\(=\left(a^2+4b^2-5+4ab+4\right)\left(a^2+4b^2-5-4ab-4\right)\)

\(=\left(a^2+4b^2+4ab-1\right)\left(a^2+4b^2-4ab-9\right)\)

\(=\left(\left(a+2b\right)^2-1\right)\left(\left(a-2b\right)^2-9\right)\)

\(=\left(a+2b-1\right)\left(a+2b+1\right)\left(a-2b+3\right)\left(a-2b-3\right)\)

14 tháng 2 2017

b/ \(x^4+6x^3+7x^2-6x+1\)

\(=\left(x^4+6x^3+9x^2\right)-\left(2x^2+6x\right)+1\)

\(=\left(x^2+3x\right)^2-2\left(x^2+3x\right)+1\)

\(=\left(x^2+3x-1\right)^2\)

13 tháng 9 2017

a,\(=x^3-x^2+5x^2-5x-24x+24\)

\(=x^2\left(x-1\right)+5x\left(x-1\right)-24\left(x-1\right)\)

\(=\left(x-1\right)\left(x^2+5x-24\right)\)

\(=\left(x-1\right)\left(x^2-3x+8x-24\right)\)

\(=\left(x-1\right)\left(x\left(x-3\right)+8\left(x-3\right)\right)\)

\(=\left(x-1\right)\left(x-3\right)\left(x+8\right)\)

13 tháng 9 2017

a)=(x-3)(x-1)(x+8)

b)=(x2+3x-1)2

29 tháng 10 2018

\(x^5+x^4+1\)

\(=x^5+x^4+x^3-x^3-x^2-x+x^2+x+1\)

\(=x^3\left(x^2+x+1\right)-x\left(x^2+x+1\right)+\left(x^2+x+1\right)\)

\(=\left(x^3-x+1\right)\left(x^2+x+1\right)\)

22 tháng 5 2015

A=x^4+6x^3+7x^2–6x+1=x^4+(6x^3–2x^2)+(9x^2–6x+1)
= x^4+2x^2(3x–1)+(3x–1)^2 =(x^2+3x–1)^2

chỉnh lại tí

22 tháng 5 2015

Đặt P(x)=x4+6x3+7x2- 6x+1

Đặt y=x2-1

=>y2=x4-2x2+1

P(x)=x4-2x2+1+6x3-6x+9x2

  =(x2-1)2+6x(x2-1)+9x2

Q(y)=y2+6xy+9x2

=(y+3x)2

P(x)=(x2-1+3x)2

16 tháng 6 2017

a)\(3x^2-8x+4\)

\(=3x^2-2x-6x+4\)

\(=x\left(3x-2\right)-2\left(3x-2\right)\)

\(=\left(x-2\right)\left(3x-2\right)\)

b)\(4x^4+81\)

\(=4x^4+36x^2+81-36x^2\)

\(=\left(2x^2+9\right)^2-36x^2\)

\(=\left(2x^2-6x+9\right)\left(2x^2+6x+9\right)\)

c)\(x^8+98x^4+1\)

\(=\left(x^8+2x^4+1\right)+96x^4\)

\(=\left(x^4+1\right)^2+16x^2\left(x^4+1\right)+64x^4-16x^2\left(x^4+1\right)+32x^4\)

\(=\left(x^4+8x^2+1\right)^2-16x^2\left(x^4-2x^2+1\right)\)

\(=\left(x^4+8x^2+1\right)^2-16x^2\left(x^4-2x^2+1\right)\)

\(=\left(x^4+8x^2+1\right)^2-\left(4x^3-4x\right)^2\)

\(=\left(x^4+4x^3+8x^2-4x+1\right)\left(x^4-4x^3+8x^2+4x+1\right)\)

d)\(x^4+6x^3+7x^2-6x+1\)

\(=x^4+3x^3-x^2+3x^3+9x^2-3x-x^2-3x+1\)

\(=x^2\left(x^2+3x-1\right)+3x\left(x^2+3x-1\right)-\left(x^2+3x-1\right)\)

\(=\left(x^2+3x-1\right)\left(x^2+3x-1\right)\)\(=\left(x^2+3x-1\right)^2\)

31 tháng 8 2016

a) 2x2-6x-x+3 = 2x(x-3) - (x-3) = (x-3)(2x-1)

b) x2-x-5x+5 = x(x-1) - 5(x-1) = (x-1)(x-5)

c) 5x(x-2y) + 2( x-2y)2 = (x-2y)(5x+2x-2y) = (x-2y)(7x-2y)

chú ý : (A-B)2=(B-A)2

d) 7x(4-y)2 - (4-y)3 = ( 16-8y+y2) (7x-4+y)

31 tháng 8 2016

a) \(2x^2-7x+3=2x^2-6x-x+3=2x\left(x-3\right)-\left(x-3\right)=\left(x-3\right)\left(2x-1\right)\)

b) \(x^2-6x+5=x^2-5x-x+5=x\left(x-5\right)-\left(x-5\right)=\left(x-5\right)\left(x-1\right)\)

c)\(5x\left(x-2y\right)+2\left(2y-x\right)^2=5x\left(x-2y\right)+2\left(x-2y\right)^2\\ =\left(x-2y\right)\left(5x+2x-4y\right)=\left(x-2y\right)\left(7x-4y\right)\)

d) \(7x\left(y-4\right)^2-\left(4-y\right)^3=7x\left(y-4\right)+\left(y-4\right)^3=\left(y-4\right)\left(7x-y-4\right)\)

13 tháng 7 2015

1a/ x3+x2+x+1=0

x2(x+1).(x+1)=0

=>           x2(x+1)=0                     x =1

hoặc                               =>[

              x+1=0                        x=-1

 

b/(x+2)2=x+2

x2+2.x.2+2=x+2

x+x+4x+4=x+2

6x+4=x+2

....

c/(x+1)(6x2+2x)+(x-1)(6x2+2x)=0

x2-12 + (6x2+2x)2=0

=>               x2-1 = 0                   x=1

hoặc                               => [

              (6x2+2x)2=0                 x= 0